1. Field of the Invention
The present invention relates in general to continuously variable transmissions used in wheeled motor vehicles, and more particularly to the continuously variable transmissions of a toroidal type.
2. Description of the Related Art
One of the toroidal type continuously variable transmissions is shown in Japanese Patent First Provisional Publication (tokkai) 2000-199552, which generally comprises an input disc driven by an engine, an output disc connected to driving road wheels and two power rollers each being pivotally interposed between the input and output discs to effect a power transmission from the input disc to the output disc while continuously changing a rotation speed of the output disc with respect to a speed of the input disc.
In the publication, the input and output discs and power rollers are discussed on shape and mutual positioning of them for the purpose of obtaining a sufficient power transmission efficiency and a sufficiently long life of the transmission. That is, for that purpose, radius of curvature of cross section of each disc taken along a common axis of the input and output discs and an angle defined between a normal line at a point where each disc and corresponding power roller contact and an axis of rotation of the power roller are discussed.